A change-speed transmission assembly having a continuously toroidal variable transmission and a planetary gears summing transmission is known from DE 101 21 042 C1 this is designed with an input shaft and an output shaft coaxial to it. In the change-speed transmission assembly, a lower driving range for low speeds and an upper driving range with higher driving speeds can be presented, within which a transmission ratio of the change-speed transmission assembly can be changed with continuous variability by the toroidal transmission. In addition, the input shaft can be brought into drive connection with the output shaft under the bypassing of the toroidal transmission by activating a shift element in the form of a shifting clutch at a constant overall transmission ratio relationship, whereas a so-called “direct gear” is then engaged.
It is disadvantageous that, in this operating state of the change-speed transmission assembly, its transmission ratio is not continuously variable to the desired extent.
Furthermore, a change-speed transmission assembly having a toroidal transmission and a planetary transmission is known from DE 101 54 928 A1; in this, a transmission ratio range for forward travel independent of the planetary transmission can be presented. The toroidal transmission is formed in accordance with a so-called “two-chamber principle,” and features both a central intermediate shaft connected to central gears of the toroidal transmission on the drive side and to an input shaft and a concentric intermediate shaft connected in a torque-proof manner to the central gears of the toroidal transmission on the output side.
Since, in each case, an axial offset drive is provided as the drive connection between the lay shaft and the concentric intermediate shaft and between the lay shaft and an output shaft, the change-speed transmission assembly has a need for installation space that is undesirably high.
A continuously variable planetary transmission with fixed function components is known from CZ 2003-2009 A3, the planetary gears of which are designed as double truncated cones. The planetary gears are mounted on the housing side in such a manner that they can change their distance to a main axis of the planetary transmission depending on the operating state. At the planetary gears designed as double cones, pressing forces from the outside of a pair of flat rings and pressing forces taking effect from the inside of a pair of rollers have effects on the planetary gears. Both the flat rings and the rollers are adjustable in an axial direction in a mirroring manner, whereas the rollers approach each other when the flat rings move away from one another, and vice versa.
However, it is problematic here that, with the continuously variable planetary transmission, only a limited spread is available, with which a desired operating range of a vehicle cannot be presented.